This Invention relates to a storage and dispensing device for liquids and has an important application in dealing with small volumes of radioactive or toxic solutions. In present practice such materials are commonly handled by manual methods involving the use of hand held pipetting devices to remove quantities of the material from the container in which the material is supplied by the manufacturer.
The use of such manual pipetting devices to effect removal of material can expose the user to certain hazards arising from the process. In order to remove liquid from the container or vial with such a device the user is required to open the vial, insert the tip of the pipette, draw up the required volume, remove the tip from the vial and then dispense the aspirated liquid into a further container. During this process the user is exposed to the contents of the vial with the potential risk of exposure to radiation from a radioactive substance or to toxic vapors or aerosols from a toxic substance. Furthermore, during the operation the liquid contained within the tip of the pipetting device is transferred between the storage vial and the second container giving a potential risk of spillage or contamination of the working area or the user.
U.S. Pat. No. 4,671,123 discloses a pipetting device in which manual dispensing operation is replaced by a piston actuated by an electronically controlled motor. The device is however directly equivalent to the manual pipetting device in that in the handling of radioactive or toxic substances the operator is still exposed to the same degree of hazard.
The handling of such toxic or radioactive materials is often governed by local or statutory regulations that require the user accurately to record usage of the material and account for all waste disposed from experimental use of such materials. In common practice, where manual pipetting of the material is used to effect transfer of the material from the stock vial, such recording is achieved by means of a written record.
Under this practice the user of the material may record the volume removed from the vial in a log book, in some similar written record or in some cases by entry in a computer program. The user then records the disposal of the material at the end of the period of use in the same or a separate record. These records are subsequently used to account for all usage and disposal of the material and may be used to account for the material to the appropriate inspecting authorities.
This type of system suffers from reliance on the accurate maintainance of written records by the user or users of the material. In practice the method often proves to be an inaccurate and inefficient means of monitoring the use and disposal of hazardous substances. Any method which relies on a user or users making an accurate and timely entry in the record is prone to errors or omissions on the part of the user or users. The user may forget to make the appropriate entry or he may make an inaccurate entry of the quantity of material used; in either case the record does not reflect the true quantity of material remaining in the vial. This may lead either to disposal of a vial as empty when it still contains usable material or to there being an insufficient quantity for use despite an indication to the contrary in the stock records.